Re: nan

On Tuesday, 1 November 2022 14:54:01 PDT Patrick Dupre wrote:
> Hello,
> 
> Setting
> fcn(x,g,G)=-imag(1/(x+I*g)*faddeeva(x/G)
> 
> plot [-30:30] fcn(x,0.01,1)  
> 
> provides
> nan from values less than -27.28 and more than 27.28
> There is not reason for that
> The value are small, but not very small
> slightly less than
> -0.0007586274478
> 
> Any idea?

Good question.  
Something in the cerf library is setting a range error (ERANGE)
"Math result not representable".  Possibly this is due to
underflow of the real component, which we could ignore, but that is
only speculation at this point.  Note the result
  gnuplot> print faddeeva(27.)
  {2.50797207889417e-317, 0.0209102719931009}
which indicates that the real component has reached the smallest
representable IEEE double float value.

I will investigate further.

	Ethan

> 
> Thank
> ===========================================================================
>  Patrick DUPRÉ                                 | | email: [email protected]
>  Laboratoire interdisciplinaire Carnot de Bourgogne
>  9 Avenue Alain Savary, BP 47870, 21078 DIJON Cedex FRANCE
>  Tel: +33 (0)380395988                    | | Room# D114A
> ===========================================================================
> 
> 
> 
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